Allow some labels to be settable by anyone
Description including problem, use cases, benefits, and/or goals
Most people submitting bug reports and feature proposals can't self-label since they don't have the required permissions to set labels. I totally understand not wanting people to self-label their pet issue as a gitlab-ce~3857370, but we should allow people to set gitlab-ce~2278648, ~"feature proposal", and possible other labels.
Add a boolean attribute to labels to allow them to be settable by anyone.
(Alternatively, add an attribute to labels that lets us specify the lowest permission level needed to set this label. Then some labels could be even higher importance so average developers can't set them.)